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Transaction modifies data that are stored in a Database. Transaction must always pass ACID Test. Transaction has to make sure the data in database remains consistence after it modifies the database. For example: Online payment when made has to have…Read more ›

Log file is the fundamental mechanism for data recovery as it contains all the updates made in the database. Such as Transaction records as well as Check point records. Transaction Records contains mainly the following information: 1) Transaction Identifier 2) …Read more ›

Pessimistic Concurrency Control When two or more users wants to update the same record at the same time, they may end up with conflicts. Pessimistic concurrency control prevents such a situation by locking the record for the duration of a…Read more ›